•Vitamin D plays an essential role in
bone growth during adolescent years, helping to achieve peak bone mass by late
adolescence - believed to contribute to reducing age-related bone loss in later
life

A study, published in the American
Journal of Clinical Nutrition, has shown high levels of vitamin D
inadequacy in UK adolescents, and - for the first time - identified the intake
needed by adolescents in order to maintain adequate serum vitamin D levels
during the winter time. The research was undertaken by academics from the
University of Surrey's Department of Nutritional Sciences in collaboration with
colleagues from the University of Copenhagen and University College Cork.

Adolescents are particularly
vulnerable to vitamin D deficiency, and previous studies have shown that
vitamin D levels decrease during puberty. With adolescents less likely to spend
time outdoors than younger children, they experience less exposure to the sun,
which is how we naturally obtain vitamin D. Low vitamin D levels are also a
problem at northern latitudes during the winter months when the sun is not
sufficient for us to make vitamin D within our bodies, so dietary intakes
become more important.

Vitamin D optimises calcium
absorption and therefore plays an essential role in bone mineralisation and
skeletal development. Since most rapid bone growth occurs during the adolescent
years, it is vital that teenagers have sufficient levels of vitamin D in order
to achieve peak bone mass by late adolescence. This is thought to help reduce
age-related bone loss in later life.

In the trial, 110 white male and
female adolescents were given varying levels of vitamin D3 supplements, while
some were given a placebo supplement, for a 20 week period during winter. This
showed that vitamin D intakes of between 10 and ~30 ug/day are required to
maintain an adequate level of vitamin D and avoid vitamin D deficiency.

The study forms part of a four-year
EU-funded project, ODIN, which aims to investigate safe and effective ways of
improving dietary vitamin D intakes through food fortification and
bio-fortification. The key findings were presented by lead author Dr Taryn
Smith of the University of Surrey at the National Osteoporosis Society
Conference, due to be held from 7 to 9 November 2016 in Birmingham.

Dr
Taryn Smith commented, "The research has found that adolescence, the time
when bone growth is most important in laying down the foundations for later
life, is a time when vitamin D levels are inadequate. The ODIN project is
investigating ways of improving vitamin D intake through the diet - and since
it is difficult to obtain vitamin D intakes of over 10 ug/day from food sources
alone, it is looking at ways of fortifying our food to improve the vitamin D
levels of the UK population as a whole."